The invention relates to a battery clamp which contacts a generally conical battery contact consisting of lead.
When such a battery contact is contacted, there is a problem providing a defined contact force as precisely as possible for reliable contacting. In the case that the contact forces are too small, only insufficient metallic contact results between the battery contact and the battery clamp. However, if the contact forces are excessively great, this will lead to a deformation and the flowing of the battery contact material.
The most common battery clamp consists of a contact clip which is placed onto the battery contact and is then pulled together by means of a screw. The drawback of this kind of battery clamp is that the actually applied contact force can be controlled only insufficiently. On the one hand, there is the danger that by tightening the screw with a wrench a much greater tightening torque, and thus a much greater contact force, is applied than actually required. On the other hand, if the battery clamp is used for an already deformed battery contact a situation may occur where a high tightening moment for the screw is obtained, which, however, does not correspond with the actually obtained smaller contact force.
The prior art also discloses various battery clamps which use spring elements which are to ensure a constant contact force. However, these battery clamps have a comparatively complex design.
The object of the invention consists in providing a battery clamp which can be produced simply and in a cost-effective manner with fail-safe handling and can be mounted both manually and in automated fashion with a high degree of reliability while avoiding the occurrence of incorrect mounting.
This object is achieved according to the invention by a battery clamp having a connecting lug, and a contact ring which is provided with a slot so as to form two opposite clamping ends. Each clamping end includes a bent lug, and a slope. A spring engages the clamping ends of the contact ring. A blocking wedge is positioned between the bent lugs of the clamping ends and can be shifted between a mounting position in which it keeps the clamping ends of the contact ring in a spread condition, and a contact position in which it releases the clamping ends so that the spring can pull the clamping ends together. Thus, two defined states of the battery clamp are possible, namely, the mounting position, in which the battery clamp can be slipped freely onto the conical battery contact until the contact ring abuts in planar fashion against the battery contact, and the contact position, in which the contact ring is resiliently pulled together around the battery contact. The contact force applied in this case is determined by the spring design and this connection remains constant even over a prolonged period of time because of the resilient bias applied by the spring. Furthermore, the translational motion of the blocking wedge, which can be achieved simply, suffices to spread the contact ring from its contact position into its mounting position.
According to the preferred embodiment of the invention, each bent lug is provided with an arresting edge. The blocking wedge is supported on this arresting edge when the battery clamp is in its mounting position, in which the clamping ends of the contact ring are held in a spread condition. In this way, a comparatively great actuation force is required to move the blocking wedge beyond the arresting edge to reach the clamping position. This ensures that unintended transfer of the battery clamp from the mounting position to the contact position is prevented. The great actuation force to be applied also results in an advantageous kind of battery clamp mounting. If the arresting edge is designed to be sharp-edged, as is preferred, the blocking wedge cannot be moved beyond the arresting edge by a mere force of pressure. This will only be possible if the clamping ends were slightly spread beforehand. This can be achieved by forcing the battery clamp, being in the mounting position, onto the conical battery contact. The contact ring is spread slightly by the conical battery contact when the battery clamp is forced onto the battery contact by the application of a defined force, so that planar contact results. Then, the blocking wedge can slip over the arresting edge and release the clamping ends of the contact ring, so that the spring can pull the clamping ends together. The final contact force is thus determined exclusively by the spring design, however the initial contact force, i.e. when the battery clamp is forced onto the battery contact, ensures that planar contact occurs between the battery contact and the contact ring. This results in a high mounting reliability, since the transfer of the blocking wedge from its mounting position to its contact position will not be possible until the initial contact force is applied between the contact ring and the battery contact to cause a corresponding spreading of the contact ring. This initial contact force ensures a reliable fit of the battery clamp and avoids regions of a point contact between the conical battery contact and the battery clamp.
According to the preferred embodiment of the invention, it is provided that the blocking wedge is connected with a pivotally mounted covering cap. The covering cap serves both as a protection for the battery clamp and a mounting aid. The covering cap offers a suitable pressure plane in order to apply the required putting-on force by hand. The force of pressure exerted on the covering cap simultaneously serves for transferring the blocking wedge from the mounting position to the contact position. Since the putting-on of the battery clamp and the subsequent locking by transferring the blocking wedge from the mounting position to the contact position is effected in a single direction, mounting can be automated easily. Manual mounting does not make any problems either, since it only consists of forcing the battery clamp onto the battery contact. In both cases, the jolt which occurs as a result of the blocking wedge overcoming the arresting edge represents a well-noticeable indication of the fact that the mounting has been concluded successfully in both automated and manual mounting.
The covering cap is preferably provided with a lever by means of which the blocking wedge can be moved upwards via the covering cap into the mounting position. For this purpose, the lever having a suitable support must only be lifted upwards and away from the battery contact, whereby both the transfer of the contact ring from the contact position to the mounting position and the lifting of the battery clamp from the battery contact is obtained by means of a motion in a single direction.
According to a preferred embodiment of the invention the inner side of the contact ring is provided with a knurling 15. This ensures a reliable fit of the contact ring on the conical battery contact so that the contact ring cannot xe2x80x9cfloat awayxe2x80x9d upwardly.
Advantageous embodiments of the invention read from the claims.